EventBus tests fail when EventStreamConfig is not loaded:
There were 4 errors:
1) EventBusFactoryTest::testGetEventServiceName with data set "disabled service" ('disabled_stream', '_disabled_eventbus_')
Error: Class "MediaWiki\Extension\EventStreamConfig\StreamConfigs" not found
extensions/EventBus/tests/phpunit/unit/EventBusFactoryTest.php:149
2) EventBusFactoryTest::testGetEventServiceName with data set "stream without destination event service" ('stream_without_destination_ev...ervice', 'intake-main')
Error: Class "MediaWiki\Extension\EventStreamConfig\StreamConfigs" not found
extensions/EventBus/tests/phpunit/unit/EventBusFactoryTest.php:149
3) EventBusFactoryTest::testGetEventServiceName with data set "stream with explicit event service" ('other_stream', 'intake-other')
Error: Class "MediaWiki\Extension\EventStreamConfig\StreamConfigs" not found
extensions/EventBus/tests/phpunit/unit/EventBusFactoryTest.php:149
4) EventBusFactoryTest::testGetEventServiceName with data set "stream with T321557 BC setting" ('stream_with_destination_event...etting', 'intake-main')
Error: Class "MediaWiki\Extension\EventStreamConfig\StreamConfigs" not found
extensions/EventBus/tests/phpunit/unit/EventBusFactoryTest.php:149This will also cause extension that solely depends on EventBus to fail, for example WikimediaEvents.
In production we always load EventBus, but EventStreamConfig is only loaded when wmgUseEventLogging is set. Thus I don't think it should be marked a hard requirement (added to requires in extension.json).
Some EventBus test is marked to be skipped when EventStreamConfig is not loaded. The above tests should be skipped as well (and that will be enforced by CI via T407797).